Field
Aspects described herein generally relate to wireless charging, including power transmission coil configurations having increased coupling uniformity between power receiving coils and power transmission coils.
Related Art
Wireless charging or inductive charging uses a magnetic field to transfer energy between two devices. Wireless charging of a device can be implemented using charging station. Energy is sent from one device to another device through an inductive coupling. The inductive coupling is used to charge batteries or run the receiving device. The Alliance for Wireless Power (A4WP) was formed to create industry standard to deliver power through non-radiative, near field, magnetic resonance from the Power Transmitting Unit (PTU) to a Power Receiving Unit (PRU).
The A4WP defines five categories of PRU parameterized by the maximum power delivered out of the PRU resonator. Category 1 is directed to lower power applications (e.g., Bluetooth headsets). Category 2 is directed to devices with power output of about 3.5 W and Category 3 devices have an output of about 6.5 W. Categories 4 and 5 are directed to higher-power applications (e.g., tablets, netbooks and laptops).
PTUs of A4WP use an induction coil to generate a magnetic field from within a charging base station, and a second induction coil in the PRU (i.e., portable device) takes power from the magnetic field and converts the power back into electrical current to charge the battery and/or power the device. In this manner, the two proximal induction coils form an electrical transformer. Greater distances between Transmitter and receiver coils can be achieved when the inductive charging system uses magnetic resonance coupling. Magnetic resonance coupling is the near field wireless transmission of electrical energy between two coils that are tuned to resonate at the same frequency.
The exemplary aspects of the present disclosure will be described with reference to the accompanying drawings. The drawing in which an element first appears is typically indicated by the leftmost digit(s) in the corresponding reference number.